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| Try your "familiar shapes" method on this polygon, Charlotte! |
Whether it's for a coding class assignment, for a homeowner estimating carpet or flooring before a DIY project, or for another topic altogether; it seems that a great number of people are interested in how to calculate the area of irregular polygonal shapes. As you probably expected, a boatload of self-appointed freelance experts have already shared their methodology at eHow.com. As you probably also expected, several of the answers are in serious need of clarification and/or correction (though we did find one version written by a guy who appeared to know what he was talking about). Most, however, needed help -- like the instructions penned by musician, teacher and writer (in her words) Charlotte Johnson. Charlotte's entry in the dumbass sweepstakes is titled "How to Calculate the Square Feet of Odd Shapes," now living at Hunker.com (for unknown reasons).
There's a fairly simple arithmetic formula for calculating the area of any polygonal area; which requires the x-y coordinates of all the points. That's a concept that seemed to be too difficult for Charlotte (and for the several others who attempted to answer the question). Charlotte "explains" that you should just measure all the sides, plot them to scale on graph paper, and break the polygon into rectangles and triangles. Sum the areas of all those individual polygons and you have the area of your entire polygon.
That's a simplistic approach, one that works fairly well with simple polygons -- say, an L- or T-shaped space. Once you get past ten or twelve corners, though, you're probably in trouble. Charlotte also has some other problems: first, her instructions are to
"Measure all the dimensions or sides of the area..."
...advice we're not certain how to parse. And, we wondered, wouldn't doing this be a lot easier if you also included the angles between the sides? Yes, Virginia, it would... Charlotte also blows the calculation of the different areas. It's not because she incorrectly transcribed the formulas for areas of rectangles and triangles, but for the nonsensical notion that one of your polygons might be a circle. Yes, she gives her readers the formula for the area of a circle, though it's rather ummm, "tortured": |
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"For circles, multiply the radius square by 3.14 (pi). The radius of a circle is the distance from its center point to any other point on the edge of the circle."
We're still pondering that "radius square" business, not to mention the implication that the center of a circle is just a "point on the edge of the circle"...
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No, Johnson clearly had no idea what she was talking about, and her answer isn't applicable in a general sense. She claimed that one might use this method to "advertise property you want to sell," but in all honesty it's pretty worthless. That's par for the course for an eHow freelancer, which is why we hand out so many Dumbass of the Day awards to them! |
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